The present invention relates to a device for emptying powdery substances from containers.
The transporting of powdery substances such as, for example, synthetic silicas, carbon blacks, dyeing pigments, perborates, percarbonates and the like in non-returnable containers with a volume of two cubic meters is known. These containers generally are formed of a folded box for the side walls and of two slip or telescoping boxes as bottom and top cover with the dimensions 1170 mm.times.960 mm.times.1700 mm and are placed on a suitable wooden pallet dimensioned to accommodate the box. The powdery substance itself is protected against moisture by an adjustable polyethylene bag in the interior of the carton. The polyethylene bag is closed by a simple wire loop. The two cubic meter container contains as a typical material 100 kg pyrogenically produced silica.
The emptying of the conventional container, such as the two cubic meter container takes place in a known manner from the top. This operation can employ a suction nozzle, such as is known in the art (EP-A 0 033 832), if a finely divided powdery substance such as pyrogenic silica is being transported in the container. The emptying operation must take place from the top because highly dispersed substances such as e.g. pyrogenically produced silica, form bridges and do not exhibit a continuous flow. After emptying of its contents, the container itself is conveyed to another location for appropriate usage.
As a result of the recently decreed packaging regulation in Europe, there is now the requirement of taking back the two cubic meter container and reusing it for the same powdery substance. Efforts in this country, too, are being made to recycle as much as possible. However, the use as returnable containers necessitates an emptying of the powdery contents via an opening located at the bottom or in the vicinity of the bottom. Emptying by means of the suction nozzle as is known from document EP-A 0 033 832 is then no longer possible because powdery substances such as e.g. pyrogenically produced silica exhibit a poor flow behavior.
There is thus a need to develop a device for emptying powdery substances with which an emptying from containers is possible at the bottom or in the vicinity of the bottom.